How to Properly Register and Access Dependency Services in .NET MAUI Multi-Project App with WinUI3

Question

I'm building a .NET MAUI multi-project app with only WinUI 3 support. My solution consists of three projects:

MauiApp - Contains all XAML and UI-related code. DataCore - Contains managers, enums, and entities. WinUI3 - Handles database calls, logging services, picture picker, and other dependency services. I'm facing an issue with accessing a logging service from the mauiapp project. I created an ILoggingService interface in the mauiapp project and implemented it in the winui3 project. However, when I try to fetch the logging service, I always receive null.

In my previous Xamarin.Forms project, I handled this in App.xaml.cs for UWP like this, and it worked fine:(it is now also working fine in maui)

DependencyService.Register<ILoggingService, LoggingService>(); DependencyService.Register<IPicturePicker, PicturePicker>();

For .NET MAUI, I moved this logic to MauiProgram.cs in the winui3 project using: builder.Services.AddSingleton<ILoggingService, LoggingService>();

But this still isn't working, and the logging service, or picturepicker remains null when accessed in mauiapp.

How can I correctly register and access dependency services (such as ILoggingService, IPicturePicker) across different projects in a .NET MAUI multi-project solution? Specifically, how should I set this up so that services defined in the WinUI3 project are accessible in the MauiApp project?

Felix Shen · Accepted Answer · 2024-08-21 06:38:57Z

0

In Xamarin Forms, if you want to invoke native platform functionality from shared code, you may use Xamarin.Forms DependencyService. Now in MAUI, either using Conditional compilation or Partial classes and methods can help you use native code.

If you use Conditional compilation, just try

#if Windows
        //you may invoke the platform code here
#endif

Or you may use Partial classes and methods, then you should Define the cross-platform API and Implement the API per platform.

For more info, please refer to Invoke platform code.

answered Aug 21, 2024 at 6:38

Felix Shen

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3 Comments

Monal Over a year ago

Thanks!however my issue is less about invoking native platform code and is about registering & accessing dependency services across different projects in multi-project .NET MAUI soln.I have a service defined in one project-WinUI3 and need to access itin another project-MauiApp.In XamarinForms, I register services with DepndencyService.Register but in MAUI,I using builder.Services.AddSingleton in MauiProgram.cs.Despite this, my service instance is returning null when accessed in the MauiApp project.Please provide help on ensuring proper registration and access to services across projects inMAUI

Felix Shen Over a year ago

Have you tried using IServiceProvider? e.g. _loggingService = serviceProvider.GetService<ILoggingService>(); See Explicit dependency resolution

Felix Shen Over a year ago

Does this help? Maui Hybrid preload data before rendering first page

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